Comments

Daniel pointed out a couple of bugs with our handling of
value-initialization when a pack expansion expands to 0 elements. In
one, we were failing to give an error message for value-initializing an
array of unknown bound; in the other we were passing an AGGR_INIT_EXPR
into cp_finish_decl, which isn't prepared to handle it.
Tested x86_64-pc-linux-gnu, applied to trunk.